Surface air temperature for August 2017

You are here

Surface air temperature for August 2017

Surface air temperature anomaly for August 2017 relative to the August average for the period 1981-2010. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service) Download the original image

August 2017 was warmer than the 1981-2010 average over much of Europe. It was particularly warm over the south and east of the continent, where wildfires continued to trouble several countries and sustaining water supplies remained a challenge in places. Temperatures continued to be below average over the north-west.

Unusually warm summer conditions prevailed over the western USA and western and northern Canada, although central and eastern North America was not as warm as usual for August. Temperatures were much above average over parts of the Middle East and eastern Siberia. Most other continental areas were also warmer than average. Temperatures were well below average over much of Antarctica, although pronounced warm anomalies occurred where the surrounding winter sea-ice cover was lower than usual.

Surface air temperature anomaly for September 2016 to August 2017 relative to the average for 1981-2010. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service) Download the original image

Average temperatures for the twelve-month period from September 2016 to August 2017 were:

most above the 1981-2010 average in the Arctic;

much above average offshore of West Antarctica, over much of North America, and over south-western Europe, the Middle East, north-western and central Africa, and eastern and southern Asia;

higher than average over most other areas of land and ocean;

lower than average over only a few oceanic and land areas.

Monthly global-mean and European-mean surface air temperature anomalies relative to 1981-2010, from January 1979 to August 2017. The darker coloured bars denote the August values. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service)Access to data Download the original image

August 2017 extended the spell of exceptional global warmth that has now lasted since mid-2015. It was:

close to 0.5°C warmer than the average August from 1981-2010;

the second warmest August on record, by a small margin of well under 0.1°C;

more than 0.1°C cooler than August 2016.

The warmest instances of each month of the year occurred from October 2015 to September 2016. Each of the eleven months from October 2016 to August 2017 has been the second warmest on record for that month of the year.

The largest anomalies in European-average temperatures occur in wintertime, when values can vary substantially from month to month. The average for Europe in August 2017 was 1°C above the 1981-2010 norm. This compares with August anomalies of between 1.3 and 1.4°C for the record-breaking European summers of 2003, 2010 and 2015.

Running twelve-month averages of global-mean and European-mean surface air temperature anomalies relative to 1981-2010, based on monthly values from January 1979 to August 2017. The darker coloured bars are the averages for each of the calendar years from 1979 to 2016. Source: ERA-Interim. (Credit: ECMWF Copernicus Climate Change Service)Access to data Download the original image

Averaging over twelve-month periods smooths out the shorter-term variations. Globally, the twelve-month average from September 2016 to August 2017 is 0. 55°C above the 1981-2010 average. The warmest twelve-month period on record is from October 2015 to September 2016, with a temperature 0.64°C above average. 2016 is by far the warmest calendar year on record: its global temperature of 0.62°C above the average for 1981-2010 compares with the value of 0.44°C for 2015, the next warmest calendar year.

The spread in the global averages from various temperature datasets has been unusually large in 2016 and 2017, due to differences in the extent to which datasets represent the relatively warm conditions that have predominated over both the Arctic and the Antarctic. Spread is also large for the years 2005 and 2006, for which the values presented here are relatively high and likely to be reduced when production of an updated dataset has been completed. Nevertheless, there is general agreement between datasets regarding:

the exceptional warmth of 2016, and to a lesser extent 2015;

the overall rate of warming since the late 1970s;

the sustained period of above-average temperatures from 2001 onwards.

There is more variability in average European temperatures, but values are less uncertain because observational coverage of the continent is relatively dense. Twelve-month averages for Europe were at a high level from 2014 to 2016. They have fallen over the past twelve months, but remain well above the 1981-2010 average. The warmest twelve-month period occurred from July 2006 to June 2007.